web3.js

npm install web3

yarn add web3

import { Web3, HttpProvider } from 'web3';
 
// Configure provider with custom headers
const httpOptions = {
  providerOptions: {
    headers: {
      'X-API-Key': 'your-api-key'
    }
  }
};
 
// Create the provider and Web3 instance
const provider = new HttpProvider('https://rpc.256blocks.com/ethereum', httpOptions);
const web3 = new Web3(provider);
 
// Get the latest block number
const blockNumber = await web3.eth.getBlockNumber();
console.log('Latest block:', blockNumber);

import { Web3, HttpProvider } from 'web3';
 
const httpOptions = {
  providerOptions: {
    headers: {
      'X-API-Key': 'your-api-key'
    }
  }
};
 
const provider = new HttpProvider('https://rpc.256blocks.com/ethereum', httpOptions);
const web3 = new Web3(provider);
 
// Get account balance
const address = '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb';
const balance = await web3.eth.getBalance(address);
 
console.log('Balance:', web3.utils.fromWei(balance, 'ether'), 'ETH');

import { Web3, HttpProvider } from 'web3';
 
const httpOptions = {
  providerOptions: {
    headers: {
      'X-API-Key': 'your-api-key'
    }
  }
};
 
const provider = new HttpProvider('https://rpc.256blocks.com/ethereum', httpOptions);
const web3 = new Web3(provider);
 
// ERC-20 ABI (minimal)
const erc20Abi = [
  {
    name: 'balanceOf',
    type: 'function',
    stateMutability: 'view',
    inputs: [{ name: 'account', type: 'address' }],
    outputs: [{ name: '', type: 'uint256' }]
  },
  {
    name: 'decimals',
    type: 'function',
    stateMutability: 'view',
    inputs: [],
    outputs: [{ name: '', type: 'uint8' }]
  }
];
 
// USDC contract on Ethereum
const usdcAddress = '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48';
const contract = new web3.eth.Contract(erc20Abi, usdcAddress);
 
const balance = await contract.methods.balanceOf('0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb').call();
const decimals = await contract.methods.decimals().call();
 
// Convert balance to human-readable format
const formattedBalance = Number(balance) / Math.pow(10, Number(decimals));
console.log('USDC Balance:', formattedBalance);

import { Web3, HttpProvider } from 'web3';
 
function createWeb3(chain, apiKey) {
  const httpOptions = {
    providerOptions: {
      headers: {
        'X-API-Key': apiKey
      }
    }
  };
 
  const provider = new HttpProvider(`https://rpc.256blocks.com/${chain}`, httpOptions);
  return new Web3(provider);
}
 
// Create Web3 instances for different chains
const ethWeb3 = createWeb3('ethereum', 'your-api-key');
const baseWeb3 = createWeb3('base', 'your-api-key');
const arbWeb3 = createWeb3('arbitrum', 'your-api-key');
const polygonWeb3 = createWeb3('polygon', 'your-api-key');